Gyroscopic compass



Dec. 4, 1928 E. SPERW. JR

GYROSCOPIU COHPx'aSS Jan. 2,2; 1920 IHHIHHINII I ENVENTOR I Q ATTORNEY I -De-4,192s.

E. A. SPERRY. JR GYROSCOPIC COMPASS I Filed Jan- 22. 1 s Sheets-Sheet 2 ATTO NEY Dec. 4,

- 1,694,192 a. .A. SPERRY. .JR

eYnoscorIc 'coumss' Fild Jan. 2 1920 3 Sheets-Sheet 3 Jud m Q Patented 4, 1928.

UNITED STATES PA 11,694,192 TE T 'oF ic-E. f.

ELMER A. srnnnir, .13., or BROOKLYN, -:Nnw yonx, AssIcNoB'. T0 trnnsrnnnv eYno- SCOPE company, or BROOKLYN, NEW YORK,

I Gmosoorrc coiurass. -I

Application filed January 22, 1920'. Serial no. 353,212.

This invention relates to gyro'compasses and is concerned chiefly with the. rovision of a practical gyro compass especial y adapted for use on aircraft, motor boats or other light, fast moving vehicles. One of the objects of my invention is to provide powerful damping means which acts quickly to suppress oscillations mum time.

Another object is to provide simple and ef fective means to readily restore the compass go the meridian in case it has departed thererom. A further object is the construction of improved means for correcting the compass speed, and latitude.

Still another object is the provision of. sim- "ple and efiicient means for centralizing and locking the gyroscope with respect to the 7 vehicle on which it is mounted.

Other objects will become evident as the description proceeds and will be pointed out in the appended claims.

Referring-to the drawings, wherein I have shown what I now consider ferred form of my invention:

' Fig. 1 isan elevation of my improved com- .pass, parts being shown in section.

Fig. 2 is a sectional view of a detail.

Fig. 3 is a sectional view of a detail.

Fig. 4 is a horizontal sectional view taken on line- 44 of Fig. 1.,

Fig. 5 is an end elevation of parts shown readings in accordance with the heading,

in Fig.1 and comprising my improved; dampin g means.

Fig. 6 is a front elevation of a nozzle used in connection with thedamping'means. N Fig. 7 is a vertical section through said nozzle. Fig. 8 is an end view of a detail.

Fig. 9 is a plan view of a detail. Fig. 10 is a side elevation of Fig. 9..

Fig. 11 is a'plan view of-a correction device.

tion device shownin Fig. 11. I

Fig. 13 is a vertical section" 13-13 of Fig. 12. y

Fig. 14 is a view of a detail.- 5 Fig. 15 is a view of a detail. In Fig. 1 I have shown'myrcompass mounted in a suitable casing 1 provided with window openings 2 and with openings 3 for afof the compass in a miniof a ball 15 carried to be the prerotor, irrespective of-the position of the comv 9 be turned to follow up-thejmovements of Fig. 12is a vertical section ofthe correca taken on line s p I 'brushes24 tOWhICh said wires may be con nected, the brushes beirig suitably insulated fording access'to the interior. Said openings 3 may be closed by-doors 3, which are preferably provided with .knobs 4. Each door may slide at its upper and loweredges in grooves5 and -6 in the casing as shown.

ghe c asing may be supported on anyv suitable ase A. CORPORATION OF NEW YORK.

Mounted in the top of easing 1 is a bushing Sin which is rotatably mounted a rod or shaft 9. Said shaftv sup orts, at its lower end, a bracket 10 preferab y arch-shaped and carrying a ring 11 pivoted thereto. A second ring 12 is pivoted within ring 11 at right an les to-the pivots supporting ring 11' in brac et 10 and carries a depending arm 13 provided with a'bearing portion 14.

As in my prior applicationfor non-pendu lous gyro compass, filed November 8,; 1919, Serial No. 336,690, I prefer to supportthe weight of the compass through the medium by bearing portion 14 of arm 13. 'he compass is connected, in a mannor to be later'described, to a member 16 di- 1. rectly supported, through a bearing portion three phase current for driving-the gyro 16 (see Fig. 2) on ball 15; For conducting pass in azimuth with-respect to'c'asing 1, I a

have shown a containerl 'otinsulating' material carried by member 16 and divided into ,a central circu ar compartment 18 and two jannula'r compartments 19 and 20 concentrictherewith.

Pins 21, mounted in an insulating support 22 carried by .ring 12, extend into said compartments and are adapted to complete a circuit through-engagement with suitable conducting liquid, such as mercury con- 1 tained therein.

It is thus. evident that conftactbetween pins 21 and the liquidin 'con- 1 v tainer' 17 will Y "relativ e rotation between c ontainer. Itis evident, however", partments 18,19, and 20 nc'ednot be entirely j be maintained regardless. of shaft 9 and said.

circular, since they may b e-arcuate if shaft the. c'ompasscard.

that com- ,To avoid twisting of the leading in wires upon rotation of shaft 9, I have shown and fixedly attached to casing 1, as through a suitable supporting rod 25. Said brushes may cooperate with collector rings 26 mounted upon an insulating sleeve 27 on shaft 9 and suitably insulated from each other. Rings 26 and ins 21 may obviously be connected by suita le conductors, such as wires 26.

The casing in which the gyro rotor 23' is journaled is shown at 23. For supporting the gyro casing 23 I have shown a bracket 28 connected to memberlfi so as to depend therefrom, the gyro casing being ivoted to said bracket about a horizontal axisat 29 and 30. Bracket 28 may also serve to carry the compass card 31 through suitable supporting standards 32. The gyro rotor 23' is mounted in casing 23 for rotation about a horizontal axis at right angles to axis 29, in the manner well known in the art. As shown, the pivotal axis 29-30 is above the center of gravity of the gyroscope so that the gyroscope is ndulously supported.

or indicating he inclination of the gyrosco about axis 29-30, and hence the deviation of the compass from the meridian, I may provide a pair of levels'33, 34 suitably attached to ro casing 23. By wa of example I havegl iown the levels adj usta ly mounted by means of screw supports 35 and nuts 36 in brackets 37 secured to said casin Springs 38' may be interposed between t e rods of said levels and said brackets, if desired. Levels 33 and 34 are preferably of differing sensitiveness so that a more accurate indication can be secured.

A compa$ of this t pe, when mounted on an aircraft, may be suh1ect to violent oscillations. For instance, should the compass be locked to the aircraft, by means to be described later in detail, and released whenthe craft is inclined at a substantial angle, the compass may oscillate for a considerable time about the horizontal axis 29-3O before being brou ht to rest. To damp such oscillationsv in t e minimum time I have provided a quick acting and powerful-damping means constructed substantially as follows:

Communicating with the interior of the gyro casing 23 is a pair of pipes 39, 39 (see Fig. 5). I have shown the pipes as communicating at their bases with suitable chambers 40, 40', which chambers in turn communicate through slots 41, 41 with the interior of casing 23. As shown, chambers 40,40 are disposed substantially tangentially with respect to casing 23 and'thus serve to store air driven by the centrifugal force resulting from rotation of the gyro rotor, said air being forced into said chambers and out through pipes 39 and 39. Of course, if desired, pipes 39 and 39' could communicate directly with the interior of casing 23.

Said pipes may be provided with nozzle pieces similar in construction. One form of such nozzle is shown in Figs-6 and 7 in connection with pipe '39. Nozzle piece 42 is shown threaded at one end into pipe 39 and comprises at its forward end a pair of extensions 43, 44 with a passageway 45 therebe- 'the other about said jections 47 and 48 entering between extensions 43 and 44 and serving to limit the widthof passageway 45 to the desired amount.

For quickly damping oscillations of the gyroscope about horizontal axis 29--30 I have provided vanes 49, 49' adapted to coopeiate respectively with pipes 39, 39' when the gyro casing is tilted in one direction or axis. Said vanes are shown supported from bracket 28 through the medium of a cross piece 50. Preferably the vanes are adjustably mounted in said cross piece so that not only may the distance of a vane from the corresponding nozzle be varied, but also the distance between the upper edge of the vane and the lower edge of the nozzle passageway, so that the action of the dampmg means may be controlled with a high de gree of accuracy. To this end I have Iprovided the means illustrated in detail in igs. 4, 5, and 8. p

' As shown, vane 49 extends from a bracket 51,-which bracket may be adjusted in a. vertical plane, with reference to cross arm 50, by means of a screw 52 which connects said bracket with a block 53 mounted on said cross arm. Said block 53 is in turn adjustable longitudinally on cross arm 50, through the medium of a slot in said cross arm and screws 54 on the block. The mounting of vane 49 is similar to that of vane 49 and is shown in Fig. 8, wherein parts similar to those associated with vane 49 are designated by the same numerals with a prime added.

From the construction described, it will be readily apparent that normally the jets of air from pipes 39 and 39' produce equal but opposits reactions. When, however, the gyroscope tilts in one direction about horizontal axis 29-30 vane 49 will come opposite the nozzle of pipe 39, and a reaction pressure.

about the vertical axis of the gyroscope is produced which causes the gyroscope to turn about horizontal axis 29-30 back to its normal position. Likewise, when the gyroscope turns in the opposite direction, vane 49 comes opposite the nozzle of pipe 39 which results in an opposite reaction pressure about the vertical axis and consequent precession of the gyroscope about horizontal axis 29-30 to normal position. As is evident from the structure disclosed, each vane can be accurate ly adjusted with respect to its corresponding nozzle so that the vane will come into the path of the air jet upon the least turning movement of the gyro casing 23 about axis 29-30 and so that the effect of the air jet can be varied, with the result that oscillation of the gyroscope about said axis may be quickly and efiectively damped, The damping means which I- have described isof great strength as compared with the mass of the gyroscope so that the tosgue produced about the vertical axis is of s cient magnitude to cause rapid downward precession of the gyroscope about horizontal axis 29-30. The settling of the compass on the meridian isthus materially hastened.

As it maybe desirable at times to centralize and lock the gyroscope with respect to the aircraft I haveprovided an effective and practical centralizingand locking means of simple construction which may be constructed substantially as follows:

Attached in any suitable manner to the bottom of the casing 23 is a frusto-conical member 55 shown in detail in Fig. 3 and having a groove 56 in its periphery. Member 55, in'

effect, thus forms part of the casing. Adapt ed to cooperate with member 55 is a frustoconical sleeve-like member 57 to which may be secured a plurality of tubular sleeves 58.

I Each sleeve may contain a plunger 59 slidably mounted therein to engage one of its ends with groove 56. The plunger may be biased to such position by means of a spring 59 attached at one end to a lug 60-on sleeve 58 and at the other to a projection 61 on the plunger, said projection extending through a slot 62 in the sleeve. The outer ends of the plungers pass through vertical slots 63 in lower supporting sleeve 64 of casing 1. Surrounding supporting sleeve 64 is a. rotatable sleeve 65 provided with guideways 66 for operating the plungers 59. By way of illustration 1' have shown three guideways 66 (see Fig. 10), one for each plunger, though it is obvious that the number of plungers and guideways may be varied as desired. The guideways are shown as each comprising outwardly project ing portions of sleeve 65 provided with a slot 67 therebetween, which slot receives the plunger 59. Slot 67 is shown inclined from the bottom of sleeve 65 toward the top thereof and hasa substantially straight portion 67 extending for a short distance adjacent said top. Each plunger is provided at its outer end with a head 68 exterior to sleeve 65 and forced by spring 59 into engagement with the edges of guideways 66. The edges of guideways 66 surroundingslots 67 are curved rection, looking down in Figs. 4 and 9. Cam

portions 69 of guideways 66 will then cooperate with heads 68 of plungers 59 to w1thsleeve 57. Hence, by rotation of sleeve 65 in one. direction the locking plungers are retracted and the locking sleeve lowered torelease the gyroscope. Rotation of sleeve 65 in the reverse direction willobviously first opcrate to raise sleeve. 57 into engagement with member 55, thus centralizing the gyroscope,

' then to release plungers 59 so that springs 59 may bring them into engagement with groove 56 of member 55 to lock the gyroscope to the aircraft. It will readily bejsecn that, while sleeve 57. and pins 59 serve to lock the gyro about horizontal axis 29-30, they do not prevent rotation of the gyroabout a vertical axis. Consequently the gyro may, while locked, be turned about the vertical axis to restore it to the meridian,v in case it has departed therefrom.

In the construction which I have described it will be seen that rotation of the compass card 31 with relation to the aircraft can take place only to a limited extent-before some part of member 16 adjacent bearing portion 16 contacts with arm 13.- Consequently, in order to pe'rmitcomplete rotation of the compass card, arm 13 must be turned as through shaft 9 to prevent contact of said arm with member 16. For readily turning shaft 9 I have shown a knob 70 mounted on said shaft and provided with a suitablg roughened edge 71. Thus, by turning knob 0, arm 13 can be kept out of contact with member 16 and complete rotation of the compass card permitted. referably some means should be provided for indicating when'arm 13 is in such position relative to the compass card that maximum angular movement of the card can 00- cur before said arm must be moved. For example, a suitably colored pointer 7 2 may be mounted on ring 11 and may cooperate with 'a. suitably colored indication or indications on card 31 to indicate such position. Thus the operator can at a glance determine the angular relation between arm 13 and card 31 so that arm 13 can be moved before said relacard is such that maximum angular move- T ment of the card can take lace, lies op osite a white mark on one arm bracket 10. I ikewise, arm 74 may have red arrow 74 adapted to re ister with a red mark on the other arm of said bracket. The operator, by noting the position of either arrow with relation to its corresponding mark on bracket can thus and may comprise a reference member supported at its upper end from casing 1. I. have shown'said member 75 as having its upper end mounted in abushing 76 which i may besecured by means of a screw 77 to a cured sleeve or'collar 78 surrounding shaft 9 and rotatable relatively thereto. Said collar may be sup orted by, a washer 79 (see Fig. 11) s'escrew 80 to shaft 9.- V

To 0 tain accurate readings of the compass, a correction depending upon the lati tude and the speed of the craft, as well as upon the heading, must be applied. A full discussion of the necessity for and the principles underlying such corrections will be found in the patent to E., A. Sperry, Serial i No. 1,255,480,'of February 5, 1918. I prefer to ap ly such corrections to the lubber line, for w ich urpose I may use means shown in detail in Flgs. 11 and 12 and constructed substantially as follows: r Extending upwardl from. sleeve 78 1s a 'pro'ection 83 whi extends upwardly throng an arcnate slot 84 in bushing 8 and is received within a fork 85 at one end of a lever member 86 pivoted at 87 to a bracket 88 suitably secured at one end to bushingBS by screws 89 and at the other to casing 1 y screws 90. Pivoted at 91 to bracket 88 is i ajlever member 92 which lies beneath' lever 86 and is provided Wllil'bffi fork 93 within which is rewived a cam or eccentric 94 rotatable withshaft 9. Cam 94 is so designed that, when shaft 9 is; turned to follow up the movement of the compass card, a movement corresponding to the amount of turning of shaft 9, which 'inturri depends uponthe change in heading ofthe craft, will be imparted to lever 92. For transmitting this motion of lever 92 to he" lubber line'to correct the compass reading for the change in headingv and "for further flPP yin a correction dependih'gon the speed and l atitnde of the craft, '1 have shown lever 92- also provided with a groove within which is mounted a slidable member 95. Preferably member 95 is grooved on opposite sides as shown in Fig.13 into which grooves extend projecting edges 96 on lever '92. Member 95 also extends within a slot vided with an intermediate slotted portion 98 through which shaft 9 passes and by which at the same timepivotal movement of the lever with relation to the shaft is permitted. A bracket member 99, the upper surface of which is provided with curves 100 corresponding to different speeds, may be suitably secured to lever 92. Adapted to coo rate with said curves is an arm 101, attache to or integral with member 95, and provided with graduations 102 corresponding to different latitudes. Itwill thus be seenthat, if member 101 be moved to cause the graduation 102 corres onding to the latitude to intersect with t e graduation 100 corresponding to the speed ofthe craft, member 95 will be positioned in accordance with said s ed and latitude. The movement imparte by lever 92 to lever 86 and hence to projection 83 and lubber line 7 5 will vary accordingly. Thus, for zero latitude. and zero speed, member 95 would lie directly above pivot 91 of member 92 so that no motion would be transmitted to lever 86, while for other latitudes and speeds member 95 would assume different positions in slot 97 and the motion transingly varied.

It 'will now be. seen that, if shaft 9 be turned to. follow up accurately the movements of the compass card, as by the aid of pointer 72 and a suitable cooperating mark von card 31, cam or eccentric 94 will cause a certain amount of motion to be imparted to lever 92 and hence to lever86 and the lubber line. Obviously'if member 95 be now positioned in accordance with the latitude and velocity of the craft, and if eccentric 94 and associated parts be properly designed, the proper correction depending upon the speed,

mitted to the lubber line would be accordlatitude, and direction of heading of the bracket 28 as shown in Fig. 1 To aid in ap- 1 w plying the torque inthe proper direction, each arm of said bracket may be provided utt e with oppositely ointing and difierently colored. arrows as s own in Fig. 14, one colored red, for instance, and the other blue. Each arrow may indicate the direction in which the bubbles of the levels will move when a torque is applied in the direction of the arrow. If desired, one of each level may be provided with an N colored to correspond with one arrow and the other end with an S corresponding in color-with the other arrow, to indicate which end of the level will rise or fall when torque is applied in accordance 1 wit-h the corresponding arrow. As is under-' stood by those skilled in the art, the restoring of the gyro casi'ng23 to vertical position will aid the gyro to more quickly settle on,

the meridian. By watching the bubbles of the levels, the operator can determine when the gyro is departing further from the meridian of gyro case 23 may eacli be provided with a.

knob =107 108. Each knob may have thereon an arrow indicating the direction in which the gyro will precess about a vertical axis, for a griven direction of rotation of the gyro rotor, if a downward force is applied to the knob. Also each knob may be provided with the letter N or S as thecase may be, indicating whether the aforesaid precession will be towards the north or south. Thus, in Fig. 15, downward pressure on knob 107 will cause precession toward the north, while downward pressure onknob 108 will cause precession to ward the south. 1

The operation of my gyro compass will be readily understood from the foregoing. After the gyro has been unlocked by turning sleeve in the proper direction, the compass will seek themeridian and will point to the true north. Oscillations about the horizontal axis 29-30 will be readily damped by the reaction of the air jets impinging on one or the other of vanes. 49, 49'. In case the gyro becomes inclinedabout axis 29-30 and itis desired to restore it quickly by hand to its normal, vertical" position, torque may be applied to one or the other of knobs 103, 104

in the proper direction as indicated b the adj acentarrows. By turning shaft 9 to ring int po nter 72in registration with a given on the com ass card. 31, said shaft will be causedto ollow-upthe. movement of the card, and, at the same time the proper ,cor-

rection for speed, latitude, and-course will be applied, throu hicam 94'and levers92 and 86 to the lubber me, if member 95 has been positioned in accordance with said latitude tween either of arrows. 7 3' or 74 and the corres ondingly colored portionof bracket 10,

or etween pointer 72 and-the mark above referred'to, the operator may turn shaft 9 at or before the time necessarytoavoid contact between member 16 and arm 13; If, at any time, the compass should" depart from the meridian and it should be desired to reset the compass on the meridian as indicated by some other known means, as by another compass,

meridian will be materially restored to the meridian is to lock the gyro by turning sleeve 65 in the proper direction and then, by grasping handles 103 and 104, to turn the gyroscope about the vertical \:axis 'into the meridian.

In accordance with the provisions of the patent statutes, I have herein described the principle ofoperation of my'invention, to-

gether with the apparatus which I now con-- sider to represent the best embodiment thereof, but I desire to have it understood that the a paratus shown is only illustrative and that t e invention canbe carried out by other means. Also, while it is designed to' use the various features and elements in. the combination and relations described, some of these may be altered and others omitted Without interfering with the more general results outlined, and the invention extends to such use.

. Havin described my. invention, .whatv I claim an desire to secure by Letters Patent 1s the gyroscope about a vertical axis, and 11V .vane'attached to said frame and'adjacent" said jet for cooperation therewith.

tion with'a gyroscope of a jet thereon adapthe combination with agyro rotor and a journalcasing therefor, of a frame in which said casing is 'journaled formovement about a horizontal axis, a jet communicating with said casing, a vane ad acent said et, an arm connected ,Withsaidframe and a member carried bysaid arm andv justable in one plane, said vane being supported thereon for adjustment in another plane. a or speed. By noting the angular distance be- 1. In gyroscopic apparatus, the combinaf 2. In gyroscopic apparatus,-- the combina- Y ii! ed to. discharge a fluid for exertinga torque on the gyroscope, a member positioned ad acent the jet for varying the-torque exerted 1 1 thereby, and means for adjusting said mem 105 I 1 14. In a gyroscopic compass, in combination with an encased. gyroscope having a normally I horizontal spinning axis, means for mounting the samefor turning about a vertical axis an for oscillation about a horizontal axis, means for preventing pivotal movement of said 'gy-' said casing to centralize. the casing about said axis, and means including a rotatable member for moving said sleeve to locking position.

6. In gyros'copic apparatus, the combina tion with a gyro rotor and a journal casing therefor, of a frame in which said casing is mounted for oscillation about a horizontal axis, a frustro-conical extension secured to said casing, a frustro-conical sleeve adapted to engage said extension to prevent movement of said casing about said axis, and displaceable means carried by said sleeve for securin said sleeve to said extension.

7.In gyroscopic apparatus, the combination with a gyro rotor and a journal casing therefor, of a frame in which said casing is mounted for oscillation about a horizontal axis, a sleeve engageable with said casing to revent such oscillation, displaceable means or securing said sleeve to said, casing, and rotatable means for displacing said displaceable means.

8. In gyroscopic apparatus, the combination with a gyro rotor and a journal casing therefor, of a frame in which said casing is mounted for oscillation about a horizontal axis, a sleeve engageable with said casing to prevent such oscillation, dis laceable means carried by said sleeve and a apted to secure said sleeve to said casing, and rotatable means for first displacing said displaceable means and then withdrawing said sleeve from engagement with said casing.

9. In a roscopic compass comprising a gyrosco e aving three de ees of freedom, means or look and u ocking' the same about ahorizonta axis, said means permitting the same to be adjusted about the vertical axis while locked.

10. The combination with a gyrosco pivotally mounted about ahorizontal axis, of a movable member for locking the gyroscope aigeainst movement about said axis, a rotatable s eve provided with inclined slots, projections carried by said member and extending into said slots, and means whereby said sleeve may be rotated to move said member either forward or away from the locking position.

11. In gyroscopic apparatus the combination with a gyro rotor and a ournal casing therefor, of a frame in which said casing is mounted for oscillation about a horizontal axis, a sleeve movable into engagement with said casin a plunger carried by said sleeve and mova le to engage with an annular groove in said casing, means for moving said plunger, and means for moving said sleeve mto or out of locking engagement with said casing.

12. In gyroscopic apparatus, the combination with a gyro rotor and a ournal casing therefor, of a frame in which said casing is mounted for oscillation about a horizontal axis, said casing having secured thereto an acorns extension with an annular groove, a sleeve such engagement and for moving said sleeve into or out of engagement with said extension.

13. In combination with an encased gyroscope pivotally mounted about horizontal and vertical axes, means for locking the gyroscope against movement about the horizontal axis but permitting movement about the vertical axis. I i Y 14. In gyroscopic apparatus, the combination with a gyro rotor and a ournal casing therefor, of a sup rt, means mountin said casing for oscillation about a horizont axis, and means on said support including a sleeve adapted to surround a part of said casing for centralizing and locking said casing against such oscillation. v

15. In a scopic compass for use on moving vebic es, a rotatable indicating member, a reference member cooperating therewith, a rotatable shaft, an eccentric mounted thereon, a lever cooperating with said eccentric, a second lever connected to said reference member, a connection between said levers, and means for shifting said connection in accordance with the speed and'latitude of the Iylehicle. bl

16. a ic compass, a rotata e compass car% a re erence member cooperating therewi a rotatable shaft, means whereby said shaft may be rotated to followup-movements of the compass card, a lever forked .at one end, a cam on said shaft and positioned within the forked end of said ever, a second lever connected to said reference member, and a connection between said levers.

17. In a pic apparatus for use on a moving ve do, a compass card a reference member, cooperating therewi a shaft adapted to be manuall rotated to follow up movements of said car and means for transmitting motion from said shaft to said reference member, comprising means for varying the movement 0 said reference member in accordance with the speed and latitude (i the vehicle.

18.. In a .gyroscopic compass, a gyro rotor, a casing in which said rotor is journaled a frame in which said casing is mounted for oscillation about a horizontal axis, a bearing member on said frame, a support-on which said frame is mounted through said bearing member for movement about a vertical axis means for rotating said support, said bearing member and support carrying indicating means for showing when said member and support have assumed a certain position with relation to each other.

19. In a gyroscopic compass, a support, a

roscope mounted thereon for movement a out a vertical axis, a compass card movable with said gyroscope, manual means for rotating said support, and a'reference mem- B berdon said support cooperating with said car 20. In a gyroscopic compass, indicating means for showing the position of the .gyroscope in azimuth, a level for showing whether 1 the gyroscope is off the meridian, means for locking the gyroscope and means for turning the same while locked to bring it quickly to:

ward the meridian if displaced.

21. 'In gyroscopic apparatus, a gyroscope 15 pivoted for movement about axes at right angles to each other, a level having means for indicating the amount of tilting of said yroscope about one of said axes, and means or indicating the direction in which tor ue should be applied-about the other axis or causing movement of said indicating means in a given direction. I

22. In gyroscopic apparatus, a gyroscope pivoted for movement about axes at right angles to each other, there being indicating means on the gyroscope for showing the direction in which precession will occur about one axis when torque is applied in a certain fldirection about the other ax s.

In testimony whereof I have affixed my signature.

ELMEB A. SPEBRY, J1; g 

